{{indexmenu_n>2}}
====== Magnetic Variation ======

Magnetic variation, or magnetic declination, is shown on paper and raster charts, but can also be calculated using the World Magnetic Model. C source code for any platform is available at: [[http://www.ngdc.noaa.gov/geomag/WMM/soft.shtml|http://www.ngdc.noaa.gov/geomag/WMM/soft.shtml]]\\
\\
For Windows OS, compilations with a graphical user interface (GUI) are available at:

  - [[http://www.ngdc.noaa.gov/geomag/WMM/wmm_gdownload.shtml|http://www.ngdc.noaa.gov/geomag/WMM/wmm_gdownload.shtml]] and at
  - [[http://sites.google.com/site/navigationalalgorithms/|http://sites.google.com/site/navigationalalgorithms/]]

 \\ A World Magnetic Data PlugIn is available for OpenCPN since 2011.04.03 (version 0.1) at: \\ [[http://www.cruisersforum.com/forums/f134/world-magnetic-model-plugin-58167.html#post658775|http://www.cruisersforum.com/forums/f134/world-magnetic-model-plugin-58167.html#post658775]] \\
 \\
In the example hereunder (from GUI no. 2 above) the nautical translation of "Declinacion magnética y Variación anual" is: "Magnetic variation and annual change". \\
 \\
{{opencpn:software:dm.png?nolink&650x342}}
